i've also read that you should wax it or treat it just the same way as the rest of the paint, but stay away from colored wax as it can stain the film.I heard that there is a cleaner that is supposed to be great for the clear bra and helps protect it while it's protecting your car. It is call "Plexus"...like Lexus with a P in front of the name (nothing to do with Lexus...a lot of boat supply stores sell it...I ordered it on Amazon.com for about $12. Will use it and report how well it works when I get it.
The most damaging thing to the film that causes yellowing are the uv rays.
i think using the spray/liquid wax would be easier instead of the solid wax around the edges so there is minimal build up which will make where the film ends more apparent.